Light emitting device

ABSTRACT

There is presented a light emitting device, having plural light emitting elements disposed on a substrate, in which a protection element, such as a zener diode, can be disposed at an appropriate position. The light emitting device includes: a substrate; a light emitting section having plural light emitting elements disposed in a mounting area on the substrate; a positive electrode and negative electrode each having a pad section and wiring section to apply voltage to the light emitting section through the wiring sections; a protection element disposed at one of the positive electrode and negative electrode and electrically connected with the other one electrode; and a light reflecting resin formed on the substrate such as to cover at least the wiring sections and the protection element, wherein the wiring sections are formed along the periphery of the mounting area such that one end portions thereof are adjacent to each other.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation of application Ser. No. 14/966,160,filed on Dec. 11, 2015, which is a Divisional of application Ser. No.13/087,950, filed on Apr. 15, 2011 (now U.S. Pat. No. 9,245,873, issuedon Jan. 26, 2016), which claims the foreign priority benefit under Title35, United States Code, Section 119(a)-(d) of Japanese PatentApplication No. 2010-094718 filed on Apr. 16, 2010 and Japanese PatentApplication No. 2011-069193 filed on Mar. 28, 2011, all of which arehereby expressly incorporated by reference into the present application.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a light emitting device usable for alighting device such as an LED bulb, a display unit, a display, the backlight source of a liquid crystal display, and the like.

Description of the Related Art

In recent years, various kinds of light emitting devices using LEDs(light emitting diodes) as light emitting elements have been developed,because the amount of heat generation and the power consumption by LEDsare smaller than those of light sources by a filament bulb or the like,and LEDs have a longer life.

For example, Unexamined Japanese Patent Application Publication No.2006-295085 presents a light source unit, with light emitting diodes,that is provided with a base plate on which a plurality of lightemitting diode elements are mounted, a printed board arranged on the topsurface of the base plate, and cathode/anode terminal electrodes formedon the printed board such as to sandwich the area where the plurality oflight emitting diode elements are mounted.

Further, Unexamined Japanese Patent Application Publication No.2010-034487 presents a light emitting device provided with a substrateon which a glass layer is formed, a plurality of LED chips arranged onthe glass layer, and the external connection terminal of a positiveelectrode and the external connection terminal of a negative electrodeformed on the glass layer such as to sandwich the plurality of LEDchips.

Still further, to prevent an LED chip from being damaged by high-voltagestatic electricity, Unexamined Japanese Patent Application PublicationNo. 2007-227882 presents an LED package provided with an ESD protectingsection, with a zener diode or the like, that is arranged in an areawhere the lead frame on the anode side and the lead frame on the cathodeside are adjacent to each other.

Light emitting devices with arrangement of several tens of lightemitting elements on a substrate have been widely developed to improvethe brightness of a light emitting device. For such a light emittingdevice having a plurality of light emitting elements mounted thereon, itis recommended to arrange a protection element, such as theabove-described zener diode, on the substrate so as to prevent elementdestruction and deterioration of performance which could occur when anover voltage is applied to the light emitting elements on the substrate.

However, in a conventional technology, the position of arranging aprotection element has not been sufficiently considered in a case ofarranging a plurality of elements on a substrate. For example, in theUnexamined Japanese Patent Application Publication No. 2006-295085 andthe Unexamined Japanese Patent Application Publication No. 2010-034487,using a protection element is not considered at all, and no means havebeen presented for preventing element destruction and the deteriorationof performance which can occur when an over voltage is applied to aplurality of light emitting elements. Further, in Unexamined JapanesePatent Application Publication No. 2007-227882, only the position ofarranging a protection element in a case of mounting a single lightemitting element is considered, and no consideration is made regarding acase of arranging a plurality of light emitting elements on a substrate.

The present invention has been developed, addressing the above-describedproblems, and an object of the invention is to provide a light emittingdevice with a plurality of light emitting elements arranged on asubstrate, wherein a protection element with a zener diode or the likecan be arranged at an appropriate position.

SUMMARY OF THE INVENTION

In order to solve the above-described problems, a light emitting device,according to the present invention, includes: a substrate; a lightemitting section having a plurality of light emitting elements disposedin a mounting area on the substrate; a positive electrode and a negativeelectrode both of which having a pad section and a wiring section,wherein the positive and negative electrodes apply voltage to the lightemitting section through the respective wiring sections; a protectionelement that is disposed at one of the positive electrode and thenegative electrode and electrically connected with the other one of thepositive electrode and the negative electrode; and a light reflectingresin formed on the substrate such as to cover at least the wiringsections and the protection element, wherein the wiring section of thepositive electrode and the wiring section of the negative electrode areformed along a periphery of the mounting area such that one end portionsthereof are adjacent to each other.

With this arrangement, even in a case of arranging a plurality of lightemitting elements on a substrate, by forming the respective wiringsections of the positive electrode and the negative electrode along theperiphery of the mounting area such that the one end portions thereofare adjacent to each other, it is possible to dispose the protectionelement at an appropriate position. Accordingly, it is possible toprevent that the voltage between the positive electrode and the negativeelectrode becomes higher than the zener voltage, and it is therebypossible to appropriately prevent occurrence of element destruction anddeterioration of performance of light emitting elements which could becaused when an over voltage is applied.

Further, the light emitting device according to the invention ispreferably arranged to further include: a relay wiring section formedalong the periphery of the mounting area, wherein each of the pluralityof light emitting elements has a p-electrode formed on one side and ann-electrode formed on the other side, wherein the p-electrodes betweenthe wiring section of the positive electrode and the relay wiringsection are arrayed such as to face one direction with respect to themounting area, and wherein the p-electrodes between the wiring sectionof the negative electrode and the relay wiring section are arrayed suchas to face the other one direction with respect to the mounting area.

With this arrangement, the relay wiring section is formed along theperiphery of the mounting area and the light emitting elements aredisposed such that the direction is reversed at the relay wiring section8. Thereby, without making the wiring for connection of the lightemitting elements to each other be complicated, the number of seriallyconnected light emitting elements can be increased in a limited areasize of the mounting area. Further, it is possible to densely dispose aplurality of light emitting elements in a limited area size of themounting area, which makes it possible to obtain a light emitting devicewith improvement in power consumption for a certain brightness, or alight emitting device with improvement in the efficiency of lightemission for a certain power consumption.

Still further, the light emitting device according to the invention ispreferably arranged such that the plurality of light emitting elementsare electrically connected to each other both serially and in parallel.

With this arrangement, by connecting a plurality of light emittingelements to each other not only serially but also in parallel, even ifthere is a variation in the forward voltage drop between a plurality ofindividual light emitting elements, the differences between outputs oflight emitting elements connected in parallel can be reduced. Thus, itis possible to reduce variation in emitted light due to variation in theforward voltage drop between light emitting elements.

Yet further, the light emitting device according to the invention ispreferably arranged such that the mounting area is formed in a certainshape having sides which face each other, and the wiring section of thepositive electrode and the wiring section of the negative electrode areformed within a range of one side of the mounting area such that one endportions thereof are adjacent to each other.

With this arrangement, by forming the wiring sections such as to beadjacent to each other within the range of one side of the mountingarea, an area for setting the wires for electrically connecting thewiring sections and the light emitting elements can be ensured.Consequently, the number of light emitting elements to be connected withthe wiring sections, in other words, the number of light emittingelements 2 to be at the start point and the end point of each serialconnection can be increased, and the number of lines of serialconnection of light emitting elements on the mounting area can beincreased. By thus increasing the number of lines of serial connection,a plurality of light emitting elements can be densely disposed in thelimited area size of the mounting area, and it is thereby possible toobtain a light emitting device whose power consumption is improved for acertain brightness or whose light emission is improved for a certainpower consumption.

Further, the light emitting device according to the invention ispreferably arranged such that the mounting area is formed in a circularshape, and the wiring section of the positive electrode and the wiringsection of the negative electrode are formed in the periphery of thecircular mounting area such that one end portions thereof are adjacentto each other.

With this arrangement, even in a case of arranging a plurality of lightemitting elements in a circular mounting area on a substrate, by formingthe respective wiring sections of the positive electrode and thenegative electrode along the periphery of the circular mounting areasuch that the one end portions thereof are adjacent to each other, it ispossible to dispose the protection element at an appropriate position.Accordingly, it is possible to prevent that the voltage between thepositive electrode and the negative electrode becomes higher than thezener voltage, and it is thereby possible to appropriately preventoccurrence of element destruction and deterioration of performance oflight emitting elements which could be caused when an over voltage isapplied.

Still further, the light emitting device according to the invention ispreferably arranged such that the light reflecting resin is formed suchas to enclose the periphery of the mounting area.

With this arrangement, by forming the light reflecting resin such as toenclose the periphery of the mounting area, even light that goes towardthe periphery of the mounting area of the substrate can be reflected bythe light reflecting resin. Consequently, the loss in output light canbe reduced, and the light extraction efficiency of the light emittingdevice can be improved.

Yet further, the light emitting device according to the invention ispreferably arranged such that a metal film is formed on the mountingarea and the plurality of light emitting elements are disposed on themounting area through the metal film.

With this arrangement, by forming a metal film on the mounting area anddisposing the plurality of light emitting elements on the metal film, alight proceeding toward the mounting area side of the substrate can bereflected by the metal film. Accordingly, the loss in output light canbe reduced to improve the efficiency of light extraction from the lightemitting device.

Still further, the light emitting device according to the invention ispreferably arranged such that the light reflecting resin is formed suchas to cover a part of the margin of the mounting area.

With this arrangement, by forming the light reflecting resin such as tocover a part of the margin of the mounting area 1 a, it is preventedthat an area, where the substrate is exposed, is formed between thewiring sections and the metal film on the mounting area. Thus, lightthat is output from the light emitting elements can be reflected allinside the area where the light reflecting resin is formed, and the lossin the output light can be reduced to the maximum to improve the lightextraction efficiency of the light emitting device.

In a light emitting device according to the invention, even in a case ofarranging a plurality of light emitting elements on a substrate, it ispossible to prevent that the voltage between the positive electrode andthe negative electrode becomes higher than the zener voltage, and it isthereby possible to appropriately prevent occurrence of elementdestruction and deterioration of performance of light emitting elementswhich could be caused when an over voltage is applied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the entire configuration of a lightemitting device in an embodiment according to the invention;

FIG. 2 is a front view showing the configuration of a light emittingdevice in a first embodiment according to the invention;

FIG. 3 is an enlarged front view showing the configuration of the lightemitting element;

FIG. 4 is a side view showing the configuration of the light emittingdevice in the first embodiment;

FIG. 5 is a front view showing the configuration of a light emittingdevice in a second embodiment according to the invention;

FIG. 6 is a front view showing the configuration of a light emittingdevice in a third embodiment according to the invention;

FIG. 7 is a front view showing the configuration of a light emittingdevice in a fourth embodiment according to the invention;

FIG. 8 is a front view showing the configuration of a light emittingdevice in a fifth embodiment according to the invention; and

FIG. 9 is a front view showing the configuration of a light emittingdevice in a sixth embodiment according to the invention.

PREFERRED EMBODIMENTS OF THE INVENTION

A light emitting device in an embodiment according to the invention willbe described below, referring to the drawings. Incidentally, the sizesand position relationships of the members shown in the drawings may bepartially exaggerated for clear illustration. Further, in thedescription below, the same name or symbol basically represents the sameor equivalent member, and detailed description will be omitted, asappropriate. Further, in FIGS. 2, and 5 to 8, in order to show thedirections of respective light emitting elements, only four positions onthe mounting area are shown for a p electrode and an n electrode (referto FIG. 3), and showing of other positions of a p electrode and an nelectrode is omitted in these figures.

First Embodiment

A light emitting device 100 according to a first embodiment will bedescribed in detail, referring to FIGS. 1 to 4. In the descriptionbelow, the entire configuration of the light emitting device 100 will bedescribed first, and then respective configurations will be described.For the convenience of description, a light reflecting resin 6 in FIG. 2is represented by the outline thereof by lines and curves, and shown ina transparent state. In FIGS. 5 to 9 referred to by other embodiments, alight reflecting resin 6 is likewise shown in a transparent state.

Entire Configuration

The light emitting device 100 is a device used for a lighting device,such as an LED bulb, a display unit, a display, the back light source ofa liquid crystal display, and the like. As shown in FIGS. 1, 2, and 4,the light emitting device 100 mainly includes a substrate 1, a pluralityof light emitting elements 2 arranged in a mounting area 1 a of thesubstrate 1, a positive electrode 3 and a negative electrode 4 formed onthe substrate 1, a protection element 5 arranged at the positiveelectrode 3, electronic components including the light emitting elements2, the protection element 5, etc., wires W connecting the positiveelectrode 3, the negative electrode 4, etc., and a light reflectingresin 6 formed on the substrate 1. Further, the light emitting device100 is herein configured such that the light reflecting resin 6 isfilled with a sealing member 7.

Substrate

The substrate 1 is arranged to dispose electronic components, such asthe light emitting elements 2 and the protection element 5. Thesubstrate 1 is formed in a rectangular flat plate shape, as shown inFIGS. 1 and 2. Further, the mounting area 1 a is compartmentalized onthe substrate 1, as shown in FIG. 2, to dispose the plurality of lightemitting elements 2. The size of the substrate 1 is not particularlylimited, and can be appropriately selected, depending on the number ofthe light emitting elements 2 and the array intervals therebetween, thepurpose, and the intended use.

As the material of the substrate 1, an insulating material is preferablyused, and further, a material is preferably used through which lightemitted from the light emitting elements 2 and external light hardlypass. Further, materials having a certain strength are preferably used,concretely, ceramics (Al₂O₃, AlN, etc.) and resins, such as phenolresin, epoxy resin, polyimide resin, BT resin (bismaleimide triazineresin) and polyphthalamide (PPA), and the like.

Mounting Area

The mounting area 1 a is an area for arranging the plurality of lightemitting elements 2. The mounting area 1 a is compartmentalized in themiddle of the substrate 1, as shown in FIG. 2. The mounting area 1 a isformed in a certain shape having sides facing each other, and moreconcretely, formed substantially in a rectangular shape with roundedcorners, as shown in FIG. 2. The size of the mounting area 1 a is notparticularly limited, and can be appropriately selected, depending onthe number of the light emitting elements 2 and the array intervalstherebetween, the purpose, and the intended use.

In the periphery of the mounting area 1 a, when FIG. 2 is viewed fromthe front, a part of a wiring section 3 b and a part of a wiring section4 b are formed along the left side of the mounting area 1 a; anotherpart of the wiring section 4 b is formed along the lower-side of themounting area 1 a; and a relay wiring section 8 is formed along theright-side of the mounting area 1 a. The periphery of the mounting area1 a refers to a periphery with a certain distance from the margin of themounting area 1 a, as shown in FIG. 2.

The mounting area 1 a may be an area compartmentalized on the substrate1 to dispose the plurality of light emitting elements 2, in other words,may be formed as an area of the same material as that of the substrate1, however, it is preferable that a metal film is formed on the mountingarea 1 a to reflect light, and the plurality of light emitting elements2 are disposed through the metal film on the mounting area 1 a. In sucha manner, by forming a metal film on the mounting area 1 a and disposingthe plurality of light emitting elements 2 on the metal film, forexample as shown in FIG. 4, a light proceeding toward the mounting area1 a side of the substrate 1 can be reflected by the metal film.Accordingly, the loss in output light can be reduced to improve theefficiency of light extraction from the light emitting device 100.

The metal film formed on the mounting area 1 a is preferably formed byelectrolytic plating or electroless plating. The material of the metalfilm is not particularly limited as long as a material can be subjectedto plating, however, for example, Ag (silver) or Au (gold) is preferablyused, and particularly silver is preferably used. Although Au has acharacteristic of absorbing light, the light reflection ratio can beincreased by further forming a TiO₂ film on the surface of plated Au.Further, Ag has a higher light reflection ratio than that of Au, and canthereby improve the light extraction efficiency of the light emittingdevice 100 more than a case of plating with Au alone. The thickness ofthe metal film to be formed on the mounting area 1 a is not particularlylimited, and can be selected, as appropriate, depending on the purposeand the intended use.

In the present embodiment, as shown in FIGS. 1 and 4, the upper portionof the mounting area 1 a is filled with a later-described sealing member7 so that the light emitting elements 2 on the mounting area 1 a and thewires W connected to the plurality of light emitting elements 2 areprotected against dusts, water, external forces, and the like.

Light Emitting Element

A light emitting element 2 is a semiconductor element that emits lightby itself when a voltage is applied thereto. Plural light emittingelements 2 are disposed, as shown in FIG. 2, in the mounting area 1 a ofthe substrate 1, and the plural light emitting elements 2 are integratedto configure the light emitting section 20 of the light emitting device100. The light emitting elements 2 are joined to the mounting area 1 aby a joining material, not shown, and as a method of joining, a joiningmethod using, for example, soldering paste as a joining material can beemployed. It is needless to say that the light emitting section 20,shown, merely represents the area where the light emitting elements 2are mounted, and emitting light from the light emitting section 20refers to emitting light from the light emitting elements 2.

Each of the light emitting elements 2 is formed in a rectangular shape,as shown in FIG. 3. The light emitting element 2 is a face-up (FU)element that is, as shown in FIG. 3, provided with a p-electrode 2A onone side of the top surface thereof and an n-electrode 2B on the otherside. In the present embodiment, in order to separate the metal film onthe mounting area 1 a for mounting the light emitting element 2 from themetal members forming a positive electrode 3 and a negative electrode 4,as shown in FIG. 3, it is preferable to use a light emitting element 2provided with the p-electrode 2A and the n-electrode 2B formed on thesame surface side and join the surface, which is opposite to theelectrode-formed surface, with the metal film on the mounting area 1 a.

The p-electrode 2A and the n-electrode 2B are, as shown in FIG. 3,respectively provided with a p-pad electrode 2Aa and an n-pad electrode2Ba being electrode terminals, and a stretched conductive section 2Aband a stretched conductive section 2Bb being auxiliary electrodes fordiffusing a current applied into the light emitting element 2throughout. Incidentally, the light emitting element 2 can be formed ifat least the p-pad electrode 2Aa and the n-pad electrode 2Ba arearranged on the same surface side, and it is not required to provide thestretched conductive section 2Ab and the stretched conductive section2Bb. Further, though not shown, when viewed from a side, the lightemitting element 2 has a structure where a plurality of semiconductorlayers formed by n-type semiconductor layers and p-type semiconductorlayers are laminated.

As a light emitting element 2, concretely, a light emitting diode ispreferably used wherein an arbitrary wavelength can be selected for thediode, depending on the intended use. For example, as light emittingelements 2 for blue color (light with wavelength of 430 nm to 490 nm)and green color (light with wavelength of 490 nm to 570 nm), ZnSe,nitride semiconductor (In_(x)Al_(y)Ga_(1-X-Y)N, 0≤X, 0≤Y, X+Y≤1), GaP,and the like can be used. Further, as a light emitting element 2 for redcolor (light with wavelength of 620 nm to 750 nm), GaAlAs, AlInGaP, andthe like can be used.

Further, as described later, in case of introducing a fluorescentmaterial into the sealing member 7 (refer to FIG. 1), a nitridesemiconductor (In_(x)Al_(y)Ga_(1-X-Y)N, 0≤X, 0≤Y, X+Y≤1) capable ofemitting light with a short wavelength that can efficiently excite thefluorescent material is preferably used. However, the componentcomposition, the color of emitted light, the size, and the like of thelight emitting element 2 is not limited to the above, and can beselected, as appropriate, depending on the intended use. Still further,without being limited to light in the visible light region, the lightemitting element 2 can be configured with an element that outputsultraviolet light or infrared light. Yet further, for a high poweroutput, the number of the light emitting elements 2 is preferablygreater than or equal to 10, for example, in a range of 20 to 150.

The light emitting elements 2 are arrayed, as shown in FIG. 2,vertically and horizontally on the mounting area 1 a with respectiveequal intervals, and herein, in a quantity of vertical 8×horizontal 5,and 40 in total. Further, the light emitting elements 2 adjacent to eachother in the horizontal direction with respect to the mounting area 1 aare, as shown in FIG. 2, electrically and serially connected byconductive wires W. The serial connection herein refers to a state, asshown in FIG. 2, that p-electrodes 2A and n-electrodes 2B of adjacentlight emitting elements 2 are electrically connected by wires W.

Light emitting elements 2 are arrayed, as shown in FIG. 2, in the areabetween the wiring section 3 b of the positive electrode 3 and the relaywiring section 8 such that the p-electrodes 2A of the plurality of lightemitting elements 2 face towards the left side, which is one directionwith respect to the mounting area 1 a, while the n-electrodes 2B of theplurality of light emitting elements 2 face the right side, which is theother direction with respect to the mounting area 1 a.

Further, the light emitting elements 2 are arrayed, as shown in FIG. 2,in the area between the wiring section 4 b of the negative electrode 4and the relay wiring section 8 such that the p-electrodes 2A of theplurality of light emitting elements 2 face towards the right side,which is the above-described other direction of the mounting area 1 a,while the n-electrodes 2B of the plurality of light emitting elements 2face towards the left side, which is the above-described one directionof the mounting area 1 a. That is, when FIG. 2 is viewed in the plandirection, the light emitting elements 2 are disposed such that theupper group (area) and the lower group (area) are reversed from eachother in terms of direction, at the meddle of the relay wiring section8.

In the light emitting device 100 in the present embodiment, in such amanner, the relay wiring section 8 is formed along the periphery of themounting area 1 a, and the light emitting elements 2 are disposed suchthat the direction is reversed at the middle of the relay wiring section8. Thus, without making the wiring for connection of the light emittingelements 2 to each other be complicated, the number of seriallyconnected light emitting elements 2 can be increased in a limited areasize of the mounting area 1 a. Further, it is possible to denselydispose a plurality of light emitting elements 2 in a limited area sizeof the mounting area 1 a, which makes it possible to obtain a lightemitting device 100 with improvement in power consumption for a certainbrightness, or a light emitting device 100 with improvement in theefficiency of light emission for a certain power consumption.Incidentally, in the light emitting device 100 in the presentembodiment, as shown in FIG. 2, ten light emitting elements 2 areserially connected, and such serial connections are formed for fourlines.

Positive Electrode and Negative Electrode

The positive electrode 3 and the negative electrode 4 electricallyconnect the electronic components including the plurality of lightemitting elements 2 and the protection element 5 on the substrate 1,with an external power source, not shown, to apply a voltage from theexternal power source to these electronic components. That is, thepositive electrode 3 and the negative electrode 4 take the role ofelectrodes for applying a current from outside or a part of the role.

The positive electrode 3 and the negative electrode 4 are formed, asshown in FIG. 2, by a metal member on the substrate 1. The positiveelectrode 3 and the negative electrode 4, as shown in FIG. 2,respectively include a rectangular pad section (power feeding section) 3a, 4 a, and a linear wiring section 3 b, 4 b. Arrangement is made suchthat a voltage applied to the pad section 3 a, 4 a is applied to thelight emitting section 20 configured by the plurality of light emittingelements 20 via the wiring section 3 b, 4 b. Incidentally, as shown inFIG. 2, the wiring section 4 b of the negative electrode 4 is providedwith a cathode marc CM to indicate that the electrode is the cathode.

The pad sections 3 a, 4 a are arranged to be applied with the voltagefrom the external power source. The pad sections 3 a, 4 a are, as shownin FIG. 2, formed in a pair at the diagonal positions in corners on thesubstrate 1. The pad sections 3 a, 4 a are electrically connected withthe external power source, not shown, by conductive wires W.

The wiring sections 3 b, 4 b are arranged to transfer a voltage appliedto the pad sections 3 a, 4 a to the light emitting elements 2 on themounting area 1 a. The wiring sections 3 b, 4 b are, as shown in FIG. 2,formed, extending out from the pad sections 3 a, 4 a and substantiallyin an L-shape in the periphery of the mounting area 1 a.

One end portion of the wiring section 3 b and one end portion of thewiring section 4 b are formed, as shown in FIG. 2, such as to beadjacent to each other in the periphery of the mounting area 1 a. Insuch a manner, by forming the respective wiring sections 3 b, 4 b of thepositive electrode 3 and the negative electrode 4 along the periphery ofthe mounting area 1 a and having one end portions thereof be adjacent toeach other, the later-described protection element 5 can be disposed atan appropriate position even in a case of disposing a plurality of lightemitting elements 2 on the substrate 1 in the light emitting device 100.Accordingly, the voltage between the positive and negative electrodescan be prevented from becoming higher than the zener voltage, andoccurrence of element destruction and deterioration of performance ofthe light emitting elements 2 caused by application of an over voltagecan be appropriately prevented.

More concretely, the wiring sections 3 b, 4 b are preferably formed suchthat one end portions thereof are adjacent to each other within therange of one side of the substantially rectangular mounting area 1 a,shown in FIG. 2. In such a manner, by forming the wiring sections 3 b, 4b such that the one end portions thereof are adjacent to each otherwithin the range of a side of the substantially rectangular mountingarea 1 a, an area for setting the wires W for electrically connectingthe wiring sections 3 b, 4 b and the light emitting elements 2 can beensured. Consequently, the number of light emitting elements 2 to beconnected with the wiring sections 3 b, 4 b, in other words, the numberof light emitting elements 2 to be at the start point and the end pointof each serial connection can be increased, and the number of lines ofserial connection of light emitting elements 2 on the mounting area 1 acan be increased. By thus increasing the number of lines of serialconnection, a plurality of light emitting elements 2 can be denselydisposed in the limited area size of the mounting area 1 a, and it isthereby possible to obtain a light emitting device 100 whose powerconsumption is improved for a certain brightness, or whose efficiency oflight emission is improved for a certain power consumption.

The wiring sections 3 b, 4 b are preferably formed such that one endportions thereof are adjacent to each other at the midpoint within therange of one side of the substantially rectangular mounting area 1 a,shown in FIG. 2. Thereby, the number of lines of serial connectionbetween the wiring section 3 b and the relay wiring section 8, and thenumber of lines of serial connection between the wiring section 4 b andthe relay wiring section 8, can be set equal to each other. Accordingly,a plurality of light emitting elements 2 can be densely disposed in thelimited area size of the mounting area 1 a, and it is thereby possibleto obtain a light emitting device 100 whose power consumption isimproved for a certain brightness, or whose efficiency of light emissionis improved for a certain power consumption.

Au is preferably used as the material of the metal members that form thepositive electrode 3 and the negative electrode 4. This is because, asdescribed later, when Au, which has an improved thermal conductance, isused as the material of the wires W, the wires W of the same materialcan be firmly joined.

As a method for forming the positive electrode 3 and the negativeelectrode 4, forming is preferably performed by electrolytic plating orelectroless plating similarly to the above-described method for formingthe metal film on the mounting area 1 a. The thickness of the metalmembers for forming the positive electrode 3 and the negative electrode4 is not particularly limited, and can be appropriately selected,depending on the number of wires W, the purpose, and the intended usage.

Herein, the wiring sections 3 b, 4 b are partially covered by thelater-described light reflecting resin 6, as shown in FIGS. 1 and 2.Thus, even in a case of forming the wiring sections 3 b, 4 b with Au,which tends to absorb light as described above, light out from the lightemitting elements 2 does not reach the wiring sections 3 b, 4 b and isreflected by the light reflecting resin 6. The loss in output light canbe thereby reduced, and the light extraction efficiency of the lightemitting device 100 can be improved.

Further, by covering a part of the wiring sections 3 b, 4 b by the lightreflecting resin 6, the wires W can be protected against water, externalforce, and the like. Herein, a part of the wiring sections 3 b, 4 brefers to, as shown in FIG. 2, a part, of the wiring section 3 b, 4 b,that is formed in the periphery of the mounting area 1 a and along aside of the mounting area 1 a.

In such a manner, in the light emitting device 100, the positiveelectrode 3 and the negative electrode 4, and the relay wiring section 8are arranged along the periphery of the mounting area 1 a, and thepositive electrode 3, the negative electrode 4, the relay wiring section8 are arranged on the substrate 1, being separated from the mountingarea 1 a. With such an arrangement, it is possible to use a material(for example, Au), which is capable of firmly joining with the wires W,for the positive electrode 3, the negative electrode 4, and the relaywiring section 8, and also to use a material (for example, Ag) with ahigh light reflection ratio for the mounting area 1 a. Consequently, ahighly-reliable light emitting device with an improved light extractionefficiency can be obtained.

Protection Element

The protection element 5 is an element for protecting the light emittingsection 20 with a light emitting elements 2 from element destruction anddeterioration of performance which could be caused by application of anover voltage. The protection element 5 is, as shown in FIG. 2, disposedat one end portion of the wiring section 3 b of the positive electrode3, and connected with one end portion of the wiring section 4 b of thenegative electrode 4 by a wire W. However, the protection element 5 maybe disposed at the one end portion of the wiring section 4 b of thenegative electrode 4, and connected with one end portion of the wiringsection 3 b of the positive electrode 3 by a wire W.

Concretely, the protection element 5 is configured with a zener diode,which becomes into a conduction state when applied with a voltage higherthan a prescribed voltage. The protection element 5 is a semiconductorelement having a p-electrode and an n-electrode, not shown, similarly tothe light emitting elements 2 described above, and is electricallyconnected with the wiring section 4 b of the negative electrode 4 by awire W such as to be reversely parallel to the p-electrode 2A and then-electrode 2B of the light emitting elements 2. A light emittingelement 2 cannot be disposed in the vicinity of the position where theprotection element 5 is arranged. Accordingly, the light emittingelement 2 on the fourth line and in the first row that is the closest tothe protection element 5 is, as shown in FIG. 2, connected by a wire Wat a position distant from the area where the protection element 5 isarranged.

By the presence of the protection element 5, even if a over voltage isapplied between the positive electrode 3 and the negative electrode 4and the voltage thereby exceeds the zener voltage, the voltage betweenthe positive and negative electrodes of the light emitting elements 2 isheld at the zener voltage, and does not become higher than the zenervoltage. Thus, by providing the protection element 5, the voltagebetween the positive and negative electrodes is prevented from exceedingthe zener voltage, and thereby, occurrence of element destruction anddeterioration of performance of the light emitting elements 2 whichcould be caused by application of an over voltage is appropriatelyprevented.

The protection element 5 is, as shown in FIG. 2, covered by thelater-described light reflecting resin 6. Thus, the protection element 5and the wire W connected to the protection element 5 are protectedagainst dusts, water, external forces, and the like. The size of theprotection element 5 is not particularly limited, and can beappropriately selected, depending on the purpose and the intended usage.

Light Reflecting Resin

The light reflecting resin 6 is arranged to reflect light that is outputfrom the light emitting elements 2. The light reflecting resin 6 isformed, as shown in FIG. 2, such as to cover a part of the wiringsections 3 b, 4 b, the relay wiring section 8, the protection element 5,and the wires W connected to these. Thus, even in a case where thewiring sections 3 b, 4 b, the relay wiring section 8, and the wires Ware formed with Au, which tends to absorb light as described above andlater, light that is output from the light emitting elements 2 does notreach the wiring sections 3 b, 4 b, the relay wiring section 8, and thewires W, and is reflected by the light reflecting resin 6. Consequently,the loss in output light can be reduced, and the light extractionefficiency of the light emitting device 100 can be improved. Further, bycovering a part of the wiring sections 3 b, 4 b, the relay wiringsection 8, the protection element 5, and the wires W connected to theseby the light reflecting resin 6, these members can be protected againstdusts, water, external forces, and the like.

The light reflecting resin 6 is preferably formed, as shown in FIGS. 1and 2, in a rectangular shape such as to enclose the mounting area 1 awhere the light emitting section 20 is formed on the substrate 1. Byforming the light reflecting resin 6 such as to enclose the periphery ofthe mounting area 1 a in such a manner, even light that goes toward theperiphery of the mounting area 1 a of the substrate 1, for example, alight that is output from light emitting elements 2 disposed on theright and left sides in FIG. 4, can be reflected by the light reflectingresin 6. Consequently, the loss in output light can be reduced, and thelight extraction efficiency of the light emitting device 100 can beimproved.

Further, the light reflecting resin 6 is preferably formed, as shown inFIG. 2, such as to cover a part of the area that corresponds to themargin of the mounting area 1 a. By forming the light reflecting resin 6in such a manner to cover a part of the margin of the mounting area 1 a,it is prevented that an area, where the substrate 1 is exposed, isformed between the wiring sections 3 b, 4 b and the metal film on themounting area 1 a. Thus, light that is output from the light emittingelements 2 can be reflected all inside the area where the lightreflecting resin 6 is formed, and the loss in the output light can bereduced to the maximum to improve the light extraction efficiency of thelight emitting device 100.

As the material of the light reflecting resin 6, an insulating materialis preferably used. Further, in order to ensure a certain strength, forexample, thermo-setting resin, thermo-plastic resin, or the like can beused. More concretely, phenol resin, epoxy resin, BT resin, PPA, siliconresin, or the like can be used. By dispersing, into an above-describedbase resin, powders of a reflecting material (for example, TiO₂, Al₂O₃,ZrO₂, MgO), which hardly absorbs light from the light emitting elements2 and has a large refractive index difference with respect to the baseresin, it is possible to efficiently reflect light. The size of thelight reflecting resin 6 is not particularly limited, and can beappropriately selected, depending on the purpose and the intended usage.Further, it is also possible to form a light reflecting member of amaterial other than resin at the position of the light reflecting resin6.

Sealing Member

The sealing member 7 is a member for protecting the light emittingelements 2, the protection element 5, the wires W, and the like disposedon the substrate 1 against dusts, water, external forces, and the like.The sealing member 7 is formed, as shown in FIGS. 1, 2, and 4, byfilling the inside of the mounting area 1 a, which is enclosed by thelight reflecting resin 6, on the substrate 1 with resin.

As the material of the sealing member 7, a translucent material capableof passing light from the light emitting elements 2 is preferable.Concretely, it is possible to use silicon resin, epoxy resin, urearesin, and the like. It is also possible to make such a material tocontain a coloring agent, a light diffusion agent, filler, a fluorescentmember, or the like.

The sealing member 7 can be formed by a single material, and also can beformed as a multiple layers in two or more. The filling amount of thesealing member 7 is appropriately an amount that covers the lightemitting elements 2, the protection element 5, the wires W, and the likedisposed in the mounting area 1 a enclosed by the light reflecting resin6. For providing the sealing member 7 with a lens function, the sealingmember 7 may be formed in a cannonball shape or a convex lens shape byraising the surface of the sealing member 7.

Fluorescent Member

It is also possible to make the sealing member 7 include a fluorescentmember as wavelength conversion member that absorbs at least a part oflight from the light emitting elements 2 and emits light with adifferent wavelength. As the fluorescent member, a member that convertslight from the light emitting elements 2 into light with a longerwavelength is preferable. Further, the fluorescent member may be formedas a single layer of one kind of fluorescent material or the like, andmay be formed as a single layer of mixture of two or more kinds offluorescent materials. Otherwise, the fluorescent member may be formedby lamination of two or more layers each of which is a single layercontaining one kind of fluorescent material or the like, or bylamination of two or more layers each of which is a single layercontaining a mixture of two or more kinds of fluorescent material or thelike.

As the material of a fluorescent member, it is possible to use, forexample, a YAG phosphor of a mixture of yttrium, aluminum, and garnet, anitride phosphor primarily activated by lanthanoid element such as Eu,Ce, etc., or an oxynitride phosphor.

Relay Wiring Section

The relay wiring section 8 is arranged to relay the wiring between thepositive electrodes 3 and the negative electrodes 4. The relay wiringsection 8 is, as shown in FIG. 2, formed by a metal member on thesubstrate 1. The relay wiring section 8 is formed in the periphery ofthe mounting area 1 a, as shown in FIG. 2, in a linear shape along oneside of the mounting area 1 a, namely the right side.

The relay wiring section 8 is covered by the light reflecting resin 6,as shown in FIG. 2. Thus, as described later, even in a case of usingAu, which tends to absorb light, as the metal member forming the relaywiring section 8, light that is output from the light emitting elements2 does not reach the relay wiring section 8 and is reflected by thelight reflecting resin 6. Consequently, the loss in output light can bereduced, and the light extraction efficiency of the light emittingdevice 100 can be improved. Further, by covering the relay wiringsection 8 with the light reflecting resin 6, the relay wiring section 8can be protected against dusts, water, external forces, and the like.

As the material of the metal member for the relay wiring section 8, Auis preferably used, similarly to the positive electrode 3 and thenegative electrode 4. This is because, in a case of using Au having animproved thermal conductivity as the material of the wires W, the wiresW of the same material can be firmly joined.

As a method for forming the metal member for the relay wiring section 8,forming is preferably performed by electrolytic plating or electrolessplating similarly to the case of the positive electrode 3 and thenegative electrode 4. The thickness of the metal member for the relaywiring section 8 is not particularly limited, and can be appropriatelyselected, depending on the number of the wires W, the purpose, and theintended usage.

In the light emitting device 100 in the present embodiment, the relaywiring section 8 is formed along the periphery of the mounting area 1 ain such a manner, and further, the light emitting elements 2 aredisposed such that the direction thereof is reversed at the relay wiringsection 8. Thus, without making the wiring for connection of the lightemitting elements 2 to each other be complicated, the number of seriallyconnected light emitting elements 2 can be increased in a limited areasize of the mounting area 1 a. Further, it is possible to denselydispose a plurality of light emitting elements 2 in a limited area sizeof the mounting area 1 a, which makes it possible to obtain a lightemitting device 100 with improvement in power consumption for a certainbrightness, or a light emitting device 100 with improvement in theefficiency of light emission for a certain power consumption.

Wire

The wires W are conductive wires for electrically connecting theelectronic components such as the light emitting elements 2 and theprotection element 5, the positive electrode 3, the negative electrode4, the relay wiring section 8, and the like. The material of the wires Wcan be metals, such as Au, Cu (copper), Pt (platinum), Al (aluminum),and the like, and an alloy of these, and particularly, Au, which has anexcellent thermo conductivity and the like, is preferably used. Thediameter of the wires W is not particularly limited, and can beappropriately selected, depending on the purpose and the intended usage.

Herein, the connection portion between the wires W, the positiveelectrode 3, the negative electrode 4, and the relay wiring section 8is, as shown in FIG. 2, covered by the light reflecting resin 6.Accordingly, even in a case of using Au, which tends to absorb light, asthe material for the wires W, as described above, light that is outputfrom the light emitting elements 2 is not absorbed by the wires W, butis reflected by the light reflecting resin 6. Consequently, the loss inoutput light can be reduced, and the light extraction efficiency of thelight emitting device 100 can be improved. Further, by covering theconnection portion between the wires W, the positive electrode 3, thenegative electrode 4, and the relay wiring section 8 with the lightreflecting resin 6, the wires can be protected against dusts, water,external forces, and the like. The light extracted from the lightemitting device 100 is, as shown in FIGS. 1 and 4, light extracted fromthe surface of the sealing member 7 enclosed by the light reflectingresin 6. That is, the surface of the sealing member 7 is the lightemitting surface of the light emitting device 100.

Operation of Light Emitting Device

Regarding the light emitting device 100 having been described above,when the light emitting device 100 is driven, from lights going out fromthe light emitting elements 2 into all directions, lights going upwardis extracted outside above the light emitting device 100. Further,lights going below and lights going into horizontal directions and otherdirections reflect on the bottom surface or the side surfaces in themounting area 1 a of the substrate 1, resulting in being extracted abovethe light emitting device 100. Herein, the bottom surface of thesubstrate 1, in other words, the mounting area 1 a is preferably coveredwith a metal film, and the light reflecting resin 6 is formed around themounting area 1 a. Accordingly, absorption of light at this portion isreduced and light is reflected by the metal film and the lightreflecting resin 6. Consequently, light from the light emitting elements2 is efficiently extracted. Further, for the light emitting device 100,as it is possible to increase the number of light emitting elements 2 tobe serially connected by the relay wiring section 8, it is possible toimprove the power consumption for a certain brightness, or improve theefficiency of light emission for a certain power consumption.

Method for Manufacturing Light Emitting Device

A method for manufacturing the light emitting device 100 in the firstembodiment according to the invention will be briefly described below.The method for manufacturing the light emitting device 100 includes asubstrate producing process, a plating process, a die bonding process, awire bonding process, and a light reflecting resin forming process.Further, subsequent to the light reflecting resin forming process, asealing member filling process may be included. Still further, herein, aprotection element joining process is included. The respective processeswill be described below. Incidentally, as the configuration of the lightemitting device 100 has been described above, description will beomitted below, as appropriate.

Substrate Producing Process

The substrate producing process is a process for producing the substrate1 provided with wires for plating. In the substrate producing process,the substrate 1 is formed by patterning the portions to be the mountingarea 1 a, the positive electrode 3, and the negative electrode 4 on thesubstrate 1 into certain shapes. Further, in the substrate producingprocess, wires for plating are formed for forming a metal film in themounting area 1 a on the substrate 1 by electrolytic plating.

Plating Process

The plating process is a process for forming at least metal members forthe positive electrode 3 and the negative electrode 4 on the substrate 1provided with the above-described wires, wherein the metal members forthe positive electrode 3 and the negative electrode 4 are formedpreferably by electroless plating, and a metal film is formed on themounting area 1 a of the substrate 1 by electrolytic plating. Further,in providing the relay wiring section 8, a metal member is formed in aprocess similar to the process for the positive electrode 3 and thenegative electrode 4.

As a concrete method for plating, there are methods, such as a method byperforming Au plating on the positive electrode 3 and the negativeelectrode 4, and the metal film on the mounting area 1 a as well; amethod by performing Au plating only on the positive electrode 3 and thenegative electrode 4 without forming a metal film on the mounting area 1a; and a method by performing Au plating on the positive electrode 3 andthe negative electrode 4 and performing Ag plating on the mounting area1 a. Further, a film of TiO₂ is preferably formed, on the surface of Auor Ag in the case of performing AU plating or Ag plating on the mountingarea 1 a, or directly on the surface of the substrate 1 in the case ofnot performing plating.

Die Bonding Process

The die bonding process is a process for mounting light emittingelements 2 on the above-described metal film. The die bonding processperforms a light emitting element mounting process for mounting lightemitting elements 2 on the metal film on the mounting area 1 a through ajoining material, and a heating process for joining the light emittingelements 2 on the metal film on the mounting area 1 a by heating thejoining material after mounting the light emitting elements 2.

Protection Element Joining Process

The protection element joining process is a process for mounting andjoining the protection element 5 on the wiring section 3 b of thepositive electrode 3. A method for mounting and joining the protectionelement 5 is similar to the above-described die bonding process, anddescription is omitted here.

Wire Bonding Process

The wire bonding process, which is subsequent to the die bondingprocess, is a process for electrically connecting, with wires W, thewiring section 3 b of the metallic positive electrode 3 and the p-padelectrodes 2Aa at the top of light emitting elements 2. The wire bondingprocess is also a process for electrically connecting, with wires W, then-pad electrodes 2Ba at the top of light emitting elements 2 and thewiring sections 4 b of the metallic negative electrode 4. Further, inthis process, a plurality of light emitting elements 2 are connectedthrough the respective p-pad electrodes 2Aa and the respective n-padelectrodes 2Ba. Further, electrical connection between the protectionelement 5 and the negative electrode 4 can be carried out in thisprocess. That is, the n-electrode of the protection element 5 and thewiring section 4 b of the negative electrode 4 are connected with wiresW. The method for connecting with wires W is not particularly limited,and an ordinarily used method can be employed.

Light Reflecting Resin Forming Process

The light reflecting resin forming process, which is subsequent to thewire bonding process, is a process for forming the light reflectingresin 6 such that the light reflecting resin 6 covers at least a part ofthe wiring section 3 b and the wiring section 4 b, and the relay wiringsection 8, along the margin of the mounting area 1 a. Forming the lightreflecting resin 6 can be performed, for example, using a resin ejectingdevice that is movable with respect to the substrate 1 in the verticaldirection or in the horizontal direction, above the fixed substrate 1(refer to JP 2009-182307 A).

Sealing Member Filling Process

The sealing member filling process is a process for filling the insideof the light reflecting resin 6 with a translucent sealing member 7 forcovering the light emitting elements 2 and the metal film. That is, inthe sealing member filling process, the inside of the wall portionformed by the light reflecting resin 6 on the substrate 1 is filled withthe sealing member 7 that covers the light emitting elements 2, theprotection element 5, and the metal film, the wires W, etc. on themounting area 1 a, such that molten resin is injected inside the wallportion and thereafter cured by heating, irradiation with light, or thelike.

Second Embodiment

A light emitting device 101 in a second embodiment will be describedbelow, referring to FIG. 5. The light emitting device 101 has, as shownin FIG. 5, a configuration similar to that of the above-described lightemitting device 100 in the first embodiment except the state of wiringof wires W. Accordingly, overlapped elements with those of theabove-described light emitting device 100 will be given with the samesymbols, and description of them will be omitted. Further, the lightemitting device 101 has the same entire configuration (FIG. 1) and thesame configuration of light emitting elements (FIG. 3) as those of theabove-described light emitting device 100, and accordingly descriptionof these will be omitted.

In the light emitting device 101, as shown in FIG. 5, light emittingelements 2 adjacent to each other in the horizontal and verticaldirections with respect to a mounting area 1 a are electricallyconnected by conductive wires W serially and in parallel. As shown inFIG. 5, parallel connection here refers to the state of electricalconnection between p-electrodes 2A and electrical connection betweenn-electrodes 2B of light emitting elements 2 adjacent to each other.

In such a manner, by connecting the plurality of light emitting elements2 to each other not only serially but also in parallel, even if there isa variation in the forward voltage drop (hereinafter, referred to asV_(f)) between a plurality of individual light emitting elements 2, thevariation in V_(f) can be eliminated. Incidentally, V_(f) refers to avoltage required to apply a current through a light emitting diode inthe forward direction, in other words, the voltage required by a lightemitting diode to emit light.

Herein, when there is a variation in V_(f) between a plurality ofindividual light emitting elements 2, a current easily flows in a lightemitting element 2 with a low V_(f), which causes differences in outputbetween light emitting elements 2 and accordingly causes uneven lightemission. In this situation, as described above, by connecting lightemitting elements 2 in parallel, it is possible to reduce thedifferences in output between light emitting elements 2 due to variationin V_(f) between light emitting elements 2 connected in parallel, and toreduce variation in emitted light.

As described above, in a case of connecting a plurality of lightemitting elements 2 in parallel, it is preferable, as shown in FIG. 5,that among the plurality of light emitting elements 2, the lightemitting elements 2 which are directly connected with the wiringsections 3 b, 4 b, and the relay wiring section 8 are not connected witheach other in parallel. That is, in the light emitting device 101, noparallel connection is made between the respective p-electrodes 2A ofthe light emitting elements 2 respectively on 1st line/1st row and on2nd line/1st row in the mounting area 1 a, the respective p-electrodes2A being directly connected with the wiring section 3 b, between therespective n-electrodes 2B of the light emitting elements 2 respectivelyon 7th line/1st row and on 8th line/1st row in the mounting area 1 a,the respective n-electrodes 2B being directly connected with the wiringsection 4 b, between respective n-electrodes 2B respectively on 1stline/5th row, 2nd line/5th row, 3rd line/5th row, and 4th line/5th row,the respective n-electrodes 2B being directly connected with the relaywiring section 8, and between respective p-electrodes 2A respectively on5th line/5th row, 6th line/5th row, 7th line/5th row, and 8th line/5throw, the respective p-electrodes 2A being directly connected with therelay wiring section 8. Thus, the load caused by wires W can be reduced.

Third Embodiment

A light emitting device 102 in a third embodiment will be described indetail, referring to FIG. 6. The light emitting device 102 has, as shownin FIG. 6, a configuration similar to that of the above-described lightemitting device 100 in the first embodiment except the shapes of awiring section 3 b and a wiring section 4 b and the state of wiring ofwires W. Accordingly, overlapped elements with those of theabove-described light emitting device 100 will be given with the samesymbols, and description of them will be omitted. Further, the lightemitting device 102 has the same entire configuration (FIG. 1) and thesame configuration of light emitting elements (FIG. 3) as those of theabove-described light emitting device 100, and accordingly descriptionof these will be omitted.

In the light emitting device 102, as shown in FIG. 6, one end portionsof the wiring section 3 b and the wiring section 4 b are formed adjacentto each other at a corner portion of a substantially rectangularmounting area 1 a. That is, the wiring section 3 b is formedsubstantially in an L-shape, extending from a pad section 3 a to thecorner portion of the mounting area 1 a. Further, the wiring section 4 bis formed linearly, extending from a pad section 4 a to the cornerportion of the mounting area 1 a.

In the light emitting device 102 with such a configuration, by forming arelay wiring section 8 along the periphery of the mounting area 1 a anddisposing light emitting elements 2 such that the direction of the lightemitting elements 2 is reversed at the relay wiring section 8, thenumber of serially connected light emitting elements 2 can be increasedin a limited area size of the mounting area 1 a without making thewiring for connection of the light emitting elements 2 to each other becomplicated. Further, it is possible to densely dispose a plurality oflight emitting elements 2 in a limited area size of the mounting area 1a, which makes it possible to obtain a light emitting device 102 withimprovement in power consumption for a certain brightness, or a lightemitting device 102 with improvement in the efficiency of light emissionfor a certain power consumption. Further, by connecting light emittingelements 2 to each other not only serially but also in parallel, even ifthere is a variation in V_(f) between a plurality of individual lightemitting elements 2, the variation in V_(f) can be eliminated.

Fourth Embodiment

A light emitting device 103 in a fourth embodiment will be described indetail, referring to FIG. 7. The light emitting device 103 has, as shownin FIG. 7, a configuration similar to that of the above-described lightemitting device 100 in the first embodiment except the shape of a wiringsection 4 b and the state of wiring of wires W. Accordingly, overlappedelements with those of the above-described light emitting device 100will be given with the same symbols, and description of them will beomitted. Further, the light emitting device 103 has the same entireconfiguration (FIG. 1) and the same configuration of light emittingelements (FIG. 3) as those of the above-described light emitting device100, and accordingly description of these will be omitted.

In the light emitting device 103, as shown in FIG. 7, one end portion ofa wiring section 3 b and one end portion of a wiring section 4 b areformed adjacent to each other in the periphery of a mounting area 1 a.Further, a relay wiring section 8, which is independent from a positiveelectrode 3 and a negative electrode 4, is not provided, and the wiringsection 4 b of the negative electrode 4 is extended in the periphery ofthe mounting area 1 a and along the right side, which is one side of themounting area 1 a.

In the light emitting device 103 with such a configuration, by formingthe respective wiring sections 3 b, 4 b of the positive electrode 3 andthe negative electrode 4 along the periphery of the mounting area 1 aand such that one end portions thereof are adjacent to each other, it ispossible to dispose a later-described protection element 5 at anappropriate position even when a plurality of light emitting elements 2are disposed on a substrate 1 in the light emitting device 103.Accordingly, the voltage between the positive and negative electrodescan be prevented from becoming higher than the zener voltage, andoccurrence of element destruction and deterioration of performance ofthe light emitting elements 2 caused by application of an over voltagecan be appropriately prevented.

Fifth Embodiment

A light emitting device 104 in a fifth embodiment will be described indetail, referring to FIG. 8. The light emitting device 104 has, as shownin FIG. 8, a configuration similar to that of the above-described lightemitting device 101 in the second embodiment except the state of wiringof wires W. Accordingly, overlapped elements with those of theabove-described light emitting device 101 will be given with the samesymbols, and description of them will be omitted. Further, the lightemitting device 104 has the same entire configuration (FIG. 1) and thesame configuration of light emitting elements (FIG. 3) as those of theabove-described light emitting device 101, and accordingly descriptionof these will be omitted.

In the light emitting device 104, as shown in FIG. 8, wires connecting awiring section 3 b and a relay wiring section 8 and wires connecting awiring section 4 b and the relay wiring section 8 are respectivelyarranged as ladder wires. In the light emitting device 104 with such aconfiguration, by connecting a plurality of light emitting elements 2 toeach other not only serially but also in parallel, variation in V_(f)between the plurality of individual light emitting elements 2 can beeliminated.

Sixth Embodiment

A light emitting device 105 in a sixth embodiment will be described indetail, referring to FIG. 9. The light emitting device 105 has, as shownin FIG. 9, a configuration similar to that of the above-described lightemitting device 100 in the first embodiment except the shape of amounting area 1 a and the shapes of a wiring section 3 b and a wiringsection 4 b. Accordingly, overlapped elements with those of theabove-described light emitting device 100 will be given with the samesymbols, and description of them will be omitted. Further, the lightemitting device 105 has the same configuration of light emittingelements (FIG. 3) as those of the above-described light emitting device100, and accordingly description of these will be omitted.

While the mounting area 1 a in the light emitting device 100 is formedsubstantially in a rectangular shape, a mounting area 1 a in the lightemitting device 105 is formed, as shown in FIG. 9, in a circular shape.In this mounting area 1 a in the circular shape, as shown in FIG. 9, aplurality of light emitting elements 2 are arrayed in the verticaldirection and the horizontal direction with respective equal intervals.The plurality of light emitting elements 2 are, as shown in FIG. 9,disposed with a maximum quantity of 10 elements and with a minimumquantity of 3 elements in the vertical direction, with a maximumquantity of 14 elements and with a minimum quantity of 6 elements in thevertical direction, and with a total quantity of 110 elements. Further,the respective wiring sections 3 b and 4 b of a positive electrode 3 anda negative electrode 4 are, as shown in FIG. 9, formed along theperiphery of the circular mounting area such that respective both endportions thereof are adjacent to each other.

A light reflecting resin 6 is formed in a circular shape such as toenclose the mounting area 1 a where a light emitting section 20 isformed. Further, the light reflecting resin 6 is formed such as to covera part of the wiring sections 3 b, 4 b, a protection element 5, andwires W connected to these. Incidentally, symbol AM is an anode markrepresenting that a pad section 3 a is the positive electrode 3, symbol30 is a metal film formed on the mounting area, recognition mark 70 is arecognition mark for recognizing the bonding position of light emittingelements 2, and symbol 80 is the temperature measuring point of thelight emitting device light emitting device 104. These are formed byplating or the like.

In the light emitting device 105 with such a configuration, by formingthe respective wiring sections 3 b, 4 b of the positive electrode 3 andthe negative electrode 4 along the periphery of the circular mountingarea 1 a and such that one end portions thereof are adjacent to eachother, it is possible to dispose the above-described protection element5 at an appropriate position even when a plurality of light emittingelements 2 are disposed in the circular mounting area 1 a on thesubstrate 1 in the light emitting device 105. Accordingly, in the lightemitting device 105, the voltage between the positive and negativeelectrodes can be prevented from becoming higher than the zener voltage,and occurrence of element destruction and deterioration of performanceof the light emitting elements 2 caused by application of an overvoltage can be appropriately prevented.

Light emitting devices according to the invention have been concretelydescribed above, referring to embodiments for carrying out theinvention, however, the spirit of the invention is not limited to thesedescriptions, and should be broadly and widely understood, according tothe descriptions set forth in the claims of the present patentapplication. Further, it is needless to say that the spirit of theinvention includes various changes and modifications based on thesedescriptions.

The invention claimed is:
 1. A light emitting device, comprising: asubstrate; a light emitting section including a plurality of lightemitting elements disposed on a mounting area of the substrate; at leastone electrode disposed on the substrate separate from the mounting areaand having a wiring section at least part of which is located along aring shaped periphery of the light emitting section in the plan view anda pad section electrically connected with the wiring section; a wireelectrically connected to the light emitting elements and directlyconnected to the wiring section; and a protection element disposed onthe wiring section, wherein the wiring section has a continuously formedpart between a portion of the wiring section connected with the wire anda portion of the wiring section on which the protection element isdisposed, and wherein the continuously formed part has a slit, the slitbeing formed to extend substantially perpendicular to a direction inwhich the ring shaped periphery and the continuously formed part extend.2. The light emitting device according to claim 1, wherein the pluralityof light emitting elements are electrically connected to each other bothserially and in parallel.
 3. The light emitting device according toclaim 1, wherein a material of the substrate is selected from a groupconsisting of Al₂O₃, AlN, phenol resin, epoxy resin, polyimide resin, BTresin and polyphthalamide.
 4. The light emitting device according toclaim 1, wherein the light emitting elements are nitride semiconductors.5. The light emitting device according to claim 1, wherein a material ofboth the positive electrode and the negative electrode is Au.
 6. Thelight emitting device according to claim 1, wherein a material of thewires is selected from a group consisting of Au or an alloy thereof, Cuor an alloy thereof, Pt or an alloy thereof, and Al or an alloy thereof.7. The light emitting device according to claim 1, wherein between 20and 150 of the light emitting elements are disposed on the surface ofthe substrate.
 8. The light emitting device according to claim 1,wherein the at least one electrode includes a positive electrode and anegative electrode, and an end portion of the wiring section of thepositive electrode is adjacent to an end portion of the wiring sectionof the negative electrode.
 9. The light emitting device according toclaim 8, wherein the protection element is disposed on the end portionof the wiring section of the positive electrode or the end portion ofthe wiring section of the negative electrode.
 10. The light emittingdevice according to claim 1, further comprising a light reflecting resindisposed on the substrate, said light reflecting resin covering thewiring section.
 11. The light emitting device according to claim 10,wherein the light reflecting resin has a rectangular ring shape.
 12. Thelight emitting device according to claim 10, wherein the lightreflecting resin has a circular ring shape.
 13. The light emittingdevice according to claim 10, wherein a material of the light reflectingresin is a thermo-setting resin.
 14. The light emitting device accordingto claim 10, wherein a material of the light reflecting resin is athermo-plastic resin.
 15. The light emitting device according to claim10, wherein the light reflecting resin includes a material selected froma group consisting of TiO₂, Al₂O₃, ZrO₂, and MgO.
 16. The light emittingdevice according to claim 10, further comprising a sealing memberenclosed by the light reflecting resin.
 17. The light emitting deviceaccording to claim 16, wherein the sealing member is formed in a shapeof a convex lens.
 18. The light emitting device according to claim 10,wherein the pad section is formed extending out from the lightreflecting resin.
 19. The light emitting device according to claim 10,wherein the periphery of the light emitting section has a rectangularring shape.
 20. The light emitting device according to claim 10, whereinthe periphery of the light emitting section has a circular ring shape.21. The light emitting device according to claim 1, wherein thecontinuously formed part of the wiring section is disposed adjacent tothe light emitting section so as to extend alongside at least two lightemitting elements disposed on said mounting area.
 22. The light emittingdevice according to claim 1, wherein two slits are provided on oppositesides of the continuously formed part of the wiring section, each ofsaid two slits being formed to extend substantially perpendicular to thedirection in which the ring shape and the continuously formed partextend.
 23. The light emitting device according to claim 22, wherein thetwo slits are disposed at different locations along the direction inwhich the ring shape and the continuously formed part extend.
 24. Thelight emitting device according to claim 1, wherein the protectionelement comprises a Zener diode.